//为元素添加1css像素的边框
border-1px($color)
  position relative
  &::before
    position absolute
    bottom 0
    content ""
    width 100%
    height 1px
    background $color

bg-image($url)
  background-image:url($url+"@2x.png")
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
    background-image:url($url+"@3x.png")

pxToRem($px)
  $px = unit($px/50, rem)

clearfix()
  *zoom 1
  &::after
    content ""
    display block
    clear both
$color-text-l = rgba(255, 255, 255, 0.5)
$color-text-ll = rgba(255, 255, 255, 0.8)
